考前必看:2021年考研英语工学类阅读理解模拟题及答案(三十三)

发布时间:2020-10-12


英语是考研初试当中比较拉分的科目,历来令不少考生又爱又恨。许多考生的英语都有很大的进步空间,因此英语该如何学就成为了众多考生关心的重点。想要学好英语,实战经验很重要。下面,51题库考试学习网为大家带来考研初试英语科目的一些模拟试题,正在备考的小伙伴赶紧练起来吧。

Bryant Linares has one heck of a secret family recipe how to make world-class diamonds. Seven years ago his father Robert produced a diamond in a high-pressure chamber of carbon gas and dropped it into an acid solution to clean it off. When he returned the next morning he expected to find the usual yellow stone——a crude artificial diamond of some use to industry perhaps but not the stuff of dreams. At first there didn\'t seem to be any stone at all. Then he saw at the bottom of the beaker so clear it was almost invisible a perfect quarter-carat crystal of pure carbon. It was the eureka moment,” says Bryant. His father had managed what many scientists had given up on long ago to manufacture a stone that wouldn\'t look out of place on an engagement ring.

Man-made diamonds are nothing new——industry started making them in the 1950s and each year about 80 tons of low-quality synthetic diamonds are used in tools like drill bits and sanders. High-quality crystals though open up huge possibilities jewelry being the least of them. Scientists are most excited about the prospect of making diamond microchips. As chips have shrunk over the years engineers have struggled with ways of dissipating the heat they create. Because silicon the main component of semiconductors breaks down at about 200 degrees Fahrenheit some experts believe a new material will be needed in a decade or so. Diamonds might fit the bill. They can withstand 1000 degrees and electrons move through them so easily that they would tend not to heat up in the first place. Engineers could cram a lot more circuits onto a diamond-based micro-chip——if they could perfect a way of making pure crystals cheaply.

The race is on. After working in secrecy for years refining their technique the Linareses\' company Apollo Diamond now spits out 20 carats a week both for jewelry and for diamond wafers that could be fashioned into microchips. Rivals have also been busy. Gemesis a Sarasota Fla. firm has developed a diamond growth chamber”——a press that squeezes out high-quality diamonds in much the same way that the early presses made rough ones. Gemesis is making blue diamonds——rare and sought-after gemstones.

Chipmakers are also getting into the act. The Japanese firm Nippon Telegraph and Telephone has already made prototype diamond semiconductors and the Japanese government is actively promoting the technology. Most U.S. research is going on in universities and military labs but Intel has recently taken an interest. Before the technology is ready for prime time chipmakers will have to come up with a way to keep out impurities during manufacturing. And the attribute that makes diamonds so attractive——their hardness——also makes them difficult to manipulate.

The new diamonds are likely to show up first as tiny light-emitting diodesor LEDs in flat-screen displays and high-definition televisions. And then of course there\'s jewelry. Although synthetics still carry a stigma even experts can\'t tell the difference. Natural-diamond merchants claim they aren\'t worried but De Beers has made a device that can distinguish between the natural stones and the synthetics and is distributing it to jewelers. Will consumers care? We might find out next year when Gemesis is ready to market its blue diamonds in the United States.

(1):本文选自Newsweek10/25/2004 p60-61 2p 3c

(2):本文习题命题模仿对象2002年真题Text 4

1. From the first paragraph we learn that______________.

[A] All the diamonds are almost invisible.

[B] Many scientists had tried hard to make perfect crystals long time ago.

[C] His father expected to find a diamond used in industry.

[D] Diamond are produced with carbon gas.

2. Which of the following statements is not true according to the text?

[A] Diamond can withstand higher degree than silicon.

[B] The main component of semiconductors will be replaced in a few years.

[C] High-quality crystals have least usages esp. in jewelry.

[D] Engineers could not find perfect ways of making pure crystal cheaply.

3. According to the passage why can the companies increase and perfect their production

of diamond?

[A] They all work in secrecy.

[B] They have improved their techniques.

[C] They have developed their own diamond chambers.

[D] They have turned the rough diamond to high-quality ones.

4. Which of the following best defines the word attribute(Line 5 Paragraph 4)?

[A] quality

[B] contribution

[C] appearance

[D] value

5. The new diamond is Not first used in___________.

[A] LEDs

[B] flat-screen display

[C] high-definition televisions

[D] prototype diamond semiconductor

答案:B C B A D

以上就是51题库考试学习网为大家带来的全部内容,希望能给大家一些帮助。51题库考试学习网提醒:在最后阶段,调整自己的心态也是非常重要的,每年都有考生临考前放弃,所以小伙伴们要注意不要给自己太大的压力哦。另外,小伙伴们如果还有其他关于考研信息的疑问,也可以留言咨询哦。


下面小编为大家准备了 研究生入学 的相关考题,供大家学习参考。

瘀血证的脉象有


A.实脉

B.沉弦脉

C.细涩脉

D.结代脉

答案:A,B,C
解析:

维持蛋白质分子一级结构的化学键是
A.肽键 B.氢键 C.离子键 D. 二硫键

答案:A,D
解析:
维系蛋白质一级结构的化学键包括肽键(主要)、二硫键(次要)。

发展心理学家巴尔特斯认为(  )

A.发展的内容多种多样,发展是贯穿人的一生的
B.不同的内容有着相似的发展轨迹
C.每一种内容的发展都是获得与衰退的复杂结合
D.衰老可以通过干预来适当延缓
答案:A,C,D
解析:

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